Tumor growth and metastasis impacts a large number of people each year. In fact, it is estimated that well over 600,000 new cases of cancer will be diagnosed in the coming year in the United States alone (Vamer, J. A., Brooks, P. C., and Cheresh, D. A. (1995) Cell Adh. Commun. 3, 367–374). Importantly, numerous studies have suggested that the growth of all solid tumors requires new blood vessel growth for continued expansion of the tumors beyond a minimal size (Varner et al. 1995; Blood, C. H. and Zetter, B. R. (1990) Biochim. Biophys. Acta. 1032:89–118; Weidner, N. et al. (1992) J. Natl. Cancer Inst. 84:1875–1887; Weidner, N. et al. (1991). N. Engl. J. Med. 324:1–7; Brooks, P. C. et al. (1995) J. Clin. Invest. 96:1815–1822; Brooks, P. C. et al. (1994) Cell 79:1157–1164; Brooks, P. C. et al. (1996). Cell 85, 683–693; Brooks, P. C. et al (1998) Cell 92:391–400. Significantly, a wide variety of other human diseases also are characterized by unregulated blood vessel development, including ocular diseases such as macular degeneration and diabetic retinopathy. In addition, numerous inflammatory diseases also are associated with uncontrolled neovascularization such as arthritis and psoriasis (Varner et al. 1995). Angiogenesis is the physiological process by which new blood vessels develop from pre-existing vessels (Varner et al. 1995; Blood and Zetter 1990; Weidner et al. 1992). This complex process requires cooperation of a variety of molecules including growth factors, cell adhesion receptors, matrix degrading enzymes and extracellular matrix components (Varner et al. 1995; Blood and Zetter 1990; Weidner et al. 1992). Thus, therapies designed to block angiogenesis may significantly affect the growth of solid tumors. In fact, clear evidence has been provided that blocking tumor neovascularization can significantly inhibit tumor growth in various animal models, and human clinical data is beginning to support this contention as well (Varner, J. A., Brooks, P. C., and Cheresh, D. A. (1995) Cell Adh. Commun. 3, 367–374). Importantly, numerous studies have suggested that the growth of all solid tumors requires new blood vessel growth for continued expansion of the tumors beyond a minimal size (Varner et al. 1995; Blood and Zetter 1990; Weidner et al. 1992; Weidner et al. 1991; Brooks et al. 1995; Brooks et al. 1994; Brooks et al. 1997).
To this end, many investigators have focused their anti-angiogenic approaches towards growth factors and cytokines that initiate angiogenesis (Varner et al. 1995; Blood and Zetter 1990; Weidner et al. 1992; Weidner et al. 1991; Brooks et al. 1995; Brooks et al. 1994; Brooks et al. 1997). However, there is a large number of distinct growth factors and cytokines which have the capacity to stimulate angiogenesis. The therapeutic benefit of blocking a single cytokine may have only limited benefit due to this redundancy. However, little attention has been directed to other anti-angiogenic targets. Recent studies have suggested that angiogenesis requires proteolytic remodeling of the extracellular matrix (ECM) surrounding blood vessels in order to provide a microenvironment conducive to new blood vessel development (Varner et al. 1995; Blood and Zetter 1990; Weidner et al. 1992; Weidner et al. 1991; Brooks et al. 1995; Brooks et al. 1994; Brooks et al. 1997). The extracellular matrix protein collagen makes up over 25% of the total protein mass in animals and the majority of protein within the ECM. Collagen is a fibrous multi-chain triple helical protein that exists in numerous forms (Olsen, B. R. (1995) Curr. Opin. Cell Biol. 7, 720–727; Van der Rest, M., and Garrone, R. (1991) FASEB 5, 2814–2823). At least 18 genetically distinct types of collagen have been identified, many of which have distinct tissue distributions and functions (Olsen 1995; Van der Rest and Garrone 1991). Collagen type-I is the most abundant collagen type in the extracellular matrix. Collagen type-I, type-III, collagen type-IV and collagen type-V have been shown to be associated with all pre-existing blood vessels in vivo. Collagens type-I and type-IV are composed of major chains designated α1(I) and α2(I) and α1(IV) and α2(IV) respectively. The mature collagen molecule is composed of two α1l chains and one α2 chain twisted into a triple helix. In vivo, collagen is normally found in the mature triple helical form. Denaturation of the native three dimensional structure of mature triple helical collagen may expose cryptic regulatory regions that control angiogenesis. Antagonism of these cryptic regulatory regions could provide an unrecognized means for the diagnosis and inhibition of angiogenesis.
It has been proposed that inhibition of angiogenesis would be a useful therapy for restricting tumor growth. Inhibition of angiogenesis has been proposed by (1) inhibition of release of “angiogenic molecules” such as βFGF (fibroblast growth factor), (2) neutralization of angiogenic molecules, such as by use of anti-βFGF antibodies, and (3) inhibition of endothelial cell response to angiogenic stimuli. This latter strategy has received attention, and Folkman et al., Cancer Biology, 3:89–96 (1992), have described several endothelial cell response inhibitors, including collagenase inhibitors, basement membrane turnover inhibitors, angiostatic steroids, fungal-derived angiogenesis inhibitors, platelet factor 4, thrombospondin, arthritis drugs such as D-penicillamine and gold thiomalate, vitamin D3 analogs, alpha-interferon, and the like that might be used to inhibit angiogenesis. For additional proposed inhibitors of angiogenesis, see Blood and Zetter 1990; Moses et al. (1990) Science 248:1408–1410; Ingber et al. (1988) Lab. Invest., 59:44–51; and U.S. Pat. Nos. 5,092,885, 5,112,946, 5,192,744, and 5,202,352. None of the inhibitors of angiogenesis described in the foregoing references target denatured or proteolyzed collagens.